TSPLIB: Questions and answers
Q: I found a better solution than the one claimed to be optimal in TSPLIB,
is this possible?
A: This never occured so far. In
all cases when someone believed to have found a better solution, it
was not taken into account that it is exactly specified how distances
for TSPLIB problems have to computed. Typical errors are
-
evaluation of
distances for geometric problem instances as floating-point numbers,
-
false computation of geographic distances,
-
use of display coordinates for distance computations.
Q: I get wrong distances for problems of type GEO.
A: In a previous release there was a typing error in the distance
specification for these problems. The formulae for computing latitude[i]
and longitude[i] should read
latitude[i] = PI * (deg + 5.0 * min / 3.0 ) / 180.0;
longitude[i] = PI * (deg + 5.0 * min / 3.0 ) / 180.0;
Q: What does the function nint() do?
A: The function "int nint (double x)"
converts x into int format rounding to the nearest
int value, except halfway cases are rounded to the int value
larger in magnitude. This corresponds to the Fortran generic
intrinsic function nint.
Q: Are contributions still welcome?
A: Basically yes, but, in view of the many problem instances that are
already available, new instances should either be real challenge
problems or be of general interest.
Q: Is an optimal tour available for every solved problem instance?
A: No. We have included several optimal tours for testing purposes. It is
not intended to provide all optimal tours. It should still be a
challenge to find one.
Q: Are there optimal solutions available for instances other than symmetric
ones?
A: So far, no other optimal solutions have been made available.
Last change: June 26, 1995